Linear vibration modules and linear-resonant vibration modules

ABSTRACT

The current application is directed to various types of linear vibrational modules, including linear-resonant vibration modules, that can be incorporated in a wide variety of appliances, devices, and systems to provide vibrational forces. The vibrational forces are produced by linear oscillation of a weight or member, in turn produced by rapidly alternating the polarity of one or more driving electromagnets. Feedback control is used to maintain the vibrational frequency of linear-resonant vibration module at or near the resonant frequency for the linear-resonant vibration module. Both linear vibration modules and linear-resonant vibration modules can be designed to produce vibrational amplitude/frequency combinations throughout a large region of amplitude/frequency space.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.12/782,697, filed May 18, 2010 now U.S. Pat. No. 8,093,767, which claimsthe benefit of Provisional Patent Application No. 61/179,109, filed May18, 2009.

TECHNICAL FIELD

The current application is related to vibration-generating devices and,in particular, to vibration modules that can be incorporated into a widevariety of different types of electromechanical devices and systems toproduce vibrations of selected amplitudes and frequencies over a widerange of amplitude/frequency space.

BACKGROUND

Vibration-inducing motors and mechanisms have been used for many yearsin a wide variety of different consumer appliances, toys, and otherdevices and systems. Examples include vibration signals generated bypagers, vibration-driven appliances, such as hair-trimming appliances,electric toothbrushes, electric toy football games, and many otherappliances, devices, and systems. The most common electromechanicalsystem used for generating vibrations is an intentionally unbalancedelectric motor.

FIGS. 1A-B illustrate an unbalanced electric motor typically used forgenerating vibrations in a wide variety of different devices. As shownin FIG. 1A, a small, relatively low-power electric motor 102 rotates acylindrical shaft 104 onto which a weight 106 is asymmetrically ormounted. FIG. 1B shows the weight asymmetrically mounted to the shaft,looking down at the weight and shaft in the direction of the axis of theshaft. As shown in FIG. 1B, the weight 106 is mounted off-center on theelectric-motor shaft 104. FIGS. 2A-B illustrate the vibrational motionproduced by the unbalanced electric motor shown in FIGS. 1A-B. As shownin FIGS. 2A-B, the asymmetrically-mounted weight creates an ellipticaloscillation of the end of the shaft, normal to the shaft axis, when theshaft is rotated at relatively high speed by the electric motor. FIG. 2Ashows displacement of the weight and shaft from the stationary shaftaxis as the shaft is rotated, looking down on the weight and shaft alongthe shaft axis, as in FIG. 1B. In FIG. 2A, a small mark 202 is providedat the periphery of the disk-shaped end the of electric-motor shaft toillustrate rotation of the shaft. When the shaft rotates at high speed,a point 204 on the edge of the weight traces an ellipsoid 206 and thecenter of the shaft 208 traces a narrower and smaller ellipsoid 210.Were the shaft balanced, the center of the shaft would remain at aposition 212 in the center of the diagram during rotation, but thepresence of the asymmetrically-mounted weight attached to the shaft, aswell as other geometric and weight-distribution characteristics of theelectric motor, shaft, and unbalanced weight together create forces thatmove the end of the shaft along the elliptical path 210 when the shaftis rotated at relatively high speed. The movement can be characterized,as shown in FIG. 2B, by a major axis 220 and minor axis 222. ofvibration, with the direction of the major axis of vibration equal tothe direction of the major axis of the ellipsoids, shown in FIG. 2A, andthe length of the major axis corresponding to the amplitude of vibrationin this direction. In many applications, in which a linear oscillationis desired, designers seek to force themajor-axis-amplitude/minor-axis-amplitude ratio to be as large aspossible, but, because the vibration is produced by a rotational force,it is generally not possible to achieve linear oscillation. In manycases, the path traced by the shaft center may be close to circular. Thefrequency of vibration of the unbalanced electric motor is equal to therotational frequency of the electric-motor shaft, and is thereforeconstrained by the rate at which the motor can rotate the shaft. At lowrotational speeds, little vibration is produced.

While effective in producing vibrations, there are many problemsassociated with the unbalanced-electric-motor vibration-generatingunits, such as that shown in FIG. 1A, commonly used in the variousdevices, systems, and applications discussed above. First, unbalancingthe shaft of an electric motor not only produces useful vibrations thatcan be harnessed for various applications, but also producesdestructive, unbalanced forces within the motor that contribute to rapiddeterioration of motor parts. Enormous care and effort is undertaken toprecisely balance rotating parts of motors, vehicles, and other types ofmachinery, and the consequences of unbalanced rotating parts are wellknown to anyone, familiar with automobiles, machine tools, and othersuch devices and systems. The useful lifetimes of many devices andappliances, particularly hand-held devices and appliances, that employunbalanced electric motors for generating vibrations may range from afew tens of hours to a few thousands of hours of use, after which thevibrational amplitude produced by the devices declines precipitously asthe electric motor and other parts deteriorate.

A second problem with unbalanced electric motors is that they arerelatively inefficient at producing vibrational motion. A far greateramount of power is consumed by an unbalanced electrical motor to producea given vibrational force than the theoretical minimum power required toproduce the given vibrational force. As a result, many hand-held devicesthat employ unbalanced electric motors for generating vibrations quicklyconsume batteries during use.

A third problem with unbalanced electric motors, discussed above, isthat they generally produce elliptical vibrational modes. Although suchmodes may be useful in particular applications, many applications canbetter use a linear oscillation, with greater directional concentrationof vibrational forces. Linear oscillation cannot generally be producedby unbalanced electric motors.

A fourth, and perhaps most fundamental, problem associated with usingunbalanced electric motors to generate vibrations is that only a verylimited portion of the total vibrational-force/frequency space isaccessible to unbalanced electric motors. FIG. 3 shows a graph ofvibrational force with respect to frequency for various types ofunbalanced electric motors. The graph is shown as a continuoushypothetical curve, although, of course, actual data would be discrete.As shown in FIG. 3, for relatively low-power electric motors used inhand-held appliances, only a fairly narrow range of frequencies centeredabout 80 Hz (302 in FIG. 3) generate a significant vibrational force.Moreover, the vibrational force is relatively modest. The bulk of energyconsumed by an unbalanced electric motor is used to spin the shaft andunbalanced weight and to overcome frictional and inertial forces withinthe motor. Only a relatively small portion of the consumed energy istranslated into desired vibrational forces.

Because of the above-discussed disadvantages with the commonly employedunbalanced-electric-motor vibration-generation units, designers,manufacturers, and, ultimately, users of a wide variety of differentvibration-based devices, appliances, and systems continue to seek moreefficient and capable vibration-generating units for incorporation intomany consumer appliances, devices, and systems.

SUMMARY

The current application is directed to various types of linearvibrational modules, including linear-resonant vibration modules, thatcan be incorporated in a wide variety of appliances, devices, andsystems to provide vibrational forces. The vibrational forces areproduced by linear oscillation of a weight or member, in turn producedby rapidly alternating the polarity of one or more drivingelectromagnets. Feedback control is used to maintain the vibrationalfrequency of linear-resonant vibration module at or near the resonantfrequency for the linear-resonant vibration module. Both linearvibration modules and linear-resonant vibration modules can be designedto produce vibrational amplitude/frequency combinations throughout alarge region of amplitude/frequency space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-B illustrate an unbalanced electric motor typically used forgenerating vibrations in a wide variety of different devices.

FIGS. 2A-B illustrate the vibrational motion produced by the unbalancedelectric motor shown in FIGS. 1A-B.

FIG. 3 shows a graph of vibrational force with respect to frequency forvarious types of unbalanced electric motors.

FIGS. 4A-G illustrate one particular LRVM, and operation of theparticular LRVM, that represents one implementation of thelinear-resonant vibration module to which current application isdirected.

FIGS. 5A-B illustrate an H-bridge switch that can be used, in variousembodiments of the current application, to change the direction ofcurrent applied to the coil that drives linear oscillation within alinear-resonance vibration module (“LRVM”).

FIG. 6 provides a block diagram of the LRVM, illustrated in FIGS. 4A-G,that represents one implementation of the linear-resonant vibrationmodule to which current application is directed.

FIGS. 7A-C provide control-flow diagrams that illustrate the controlprogram, executed by the CPU, that controls operation of an LRVM thatrepresents one implementation of the linear-resonant vibration module towhich current application is directed.

FIG. 8 represents the range of frequencies and vibrational forces thatcan be achieved by different implementations of LRVM and LRVM controlprograms that represent embodiments of the current application.

FIG. 9 shows a plot of the amplitude/frequency space and regions in thatspace that can ,be operationally achieved by unbalanced electricalmotors and by LRVMs that represent embodiments of the currentapplication.

FIGS. 10-17 show a variety of different alternative implementations ofLRVMs that represent different embodiments of the current application.

FIG. 18 illustrates an enhancement of an implementation of thelinear-resonant vibration module to which current application isdirected shown in FIG. 16.

FIG. 19 illustrates plots of amplitude versus frequency for a high-Q anda low-Q vibration device.

FIG. 20 illustrates portions of amplitude/frequency space accessible tovarious types of vibration modules.

FIG. 21 illustrates the dependence between frequency and amplitude in alow-Q linear vibration module as well as a modified dependence that canbe obtained by control circuitry.

FIGS. 22A-23 illustrate interesting vibrational modes produced bydriving a linear-resonant vibration module simultaneously at twodifferent frequencies.

FIGS. 24A-25 illustrate incorporation of paramagnetic flux paths into alinear vibration module.

DETAILED DESCRIPTION

The current application is directed to various linear vibration modules(“LRMs”), including various types of linear-resonant vibration modules(“LRVMs”), that can be used within a wide variety of different types ofappliances, devices, and systems, to generate vibrational forces. TheLVMs and LRVMs that represent embodiments of the current application arelinear in the sense that the vibrational forces are produced by a linearoscillation of a weight or component within the LVM or LRVM, rather thanas a by-product of an unbalanced rotation, as in the case of currentlyemployed unbalanced electric motors. The linear nature of the LRVMvibration-inducing motion allows the problems associated withunbalanced-electric-motor vibrators, discussed above, to be effectivelyaddressed. An oscillating linear motion does not produce destructiveforces that quickly degrade and wear out an unbalanced electric motor. Alinearly oscillating mechanism is characterized by parameters that canbe straightforwardly varied in order to produce vibrations of a desiredamplitude and frequency over a very broad region of amplitude/frequencyspace. In many implementations of LRVMs and LVMs, the vibrationamplitude and vibration frequency can be independently controlled by auser through user-input features, including buttons, sliders, and othertypes of user-input features. Combining a linearly oscillatingvibration-inducing mechanism with feedback control, so that thefrequency of vibration falls close to the resonant frequency of theLRVM, results in optimal power consumption with respect to the amplitudeand frequency of vibration produced by the LRVM. Clearly, linearoscillation within a LRVM translates into highly direction vibrationalforces produced by an appliance or device that incorporates the LRVM.

FIGS. 4A-G illustrate one particular LRVM, and operation of theparticular LRVM, that represents one implementation of thelinear-resonant vibration module to which current application isdirected. FIGS. 4A-G all use the same illustration conventions, nextdiscussed with reference to FIG. 4A. The LRVM includes a cylindricalhousing 402 within which a solid, cylindrical mass 404, or weight, canmove linearly along the inner, hollow, cylindrically shaped chamber 406within the cylindrical housing or tube 402. The weight is a magnet, inthe described an implementation of the linear-resonant vibration moduleto which current application is directed, with polarity indicated by the“+” sign 410 on the right-hand end and the “−” sign 412 on the left-handend of the weight 404. The cylindrical chamber 406 is capped by twomagnetic disks 414 and 416 with polarities indicated by the “+” sign 418and the “−” sign 419. The disk-like magnets 414 and 418 are magneticallyoriented opposite from the magnetic orientation of the weight 404, sothat when the weight moves to either the extreme left or extreme rightsides of the cylindrical chamber, the weight is repelled by one of thedisk-like magnets at the left or right ends of the cylindrical chamber.In other words, the disk-like magnets act much like springs, tofacilitate deceleration and reversal of direction of motion of theweight and to minimize or prevent mechanical-impact forces of the weightand the end caps that close off the cylindrical chamber. Finally, a coilof conductive wire 420 girdles the cylindrical housing, or tube 402 atapproximately the mid-point of the cylindrical housing.

FIGS. 4B-G illustrate operation of the LRVM shown in FIG. 4A. When anelectric current is applied to the coil 420 in a first direction 422, acorresponding magnetic force 424 is generated in a direction parallel tothe axis of the cylindrical chamber, which accelerates. the weight 404.in the direction of the magnetic force 424. When the weight reaches apoint at or close to the corresponding disk-like magnet 414, as shown inFIG. 4C, a magnetic force due to the repulsion of the disk-like magnet414 and the weight 404, 426, is generated in the opposite direction,decelerating the weight and reversing its direction. As the weightreverses direction, as shown in FIG. 4D, current is applied in anopposite direction 430 to the coil 420, producing a magnetic force 432in an opposite direction from the direction of the magnetic force shownin FIG. 4B, which accelerates the weight 404 in a direction opposite tothe direction in which the weight is accelerated in FIG. 4B. As shown inFIG. 4E, the weight then moves rightward until, as shown in FIG. 4F, theweight is decelerated, stopped, and then accelerated in the oppositedirection by repulsion of the disk-like magnet 416. An electricalcurrent is then applied to the coil 420 in the same direction 434 as inFIG. 4B, again accelerating the solid cylindrical mass in the samedirection as in FIG. 4B. Thus, by a combination of a magnetic field withrapidly reversing polarity, generated by alternating the direction ofcurrent applied to the coil, and by the repulsive forces between theweight magnet and the disk-like magnets at each end of the hollow,cylindrical chamber, the weight linearly oscillates back and forthwithin the cylindrical housing 402, imparting a directional force at theends of the cylindrical chamber with each reversal in direction.

Clearly, the amplitude of the vibration and vibrational forces producedare related to the length of the hollow chamber in which the weightoscillates, the current applied to the coil, the mass of the weight, theacceleration of the weight produced by the coil, and the mass of theentire LRVM. All of these parameters are essentially design parametersfor the LRVM, and thus the LRVM can be designed to produce a widevariety of different amplitudes.

The frequency of the oscillation of the solid, cylindrical mass isdetermined by the frequency at which the direction of the currentapplied to the coil is changed. FIGS. 5A-B illustrate an H-bridge switchthat can be used, in various embodiments of the current application, tochange the direction of current applied to the coil that drives linearoscillation within an LRVM. FIGS. 5A-B both use the same illustrationconventions, described next with respect to FIG. 5A. The H-bridge switchreceives, as input, a directional signal d 502 and direct-current (“DC”)power 504. The direction-control signal d 502 controls four switches506-509, shown as transistors in FIG. 5A. When the input control signald 502 is high, or “1,” as shown in FIG. 5A, switches 508 and 509 areclosed and switches 506 and 507 are open, and therefore current flows,as indicated by curved arrows, such as curved arrow 510, from thepower-source input 504 to ground 512 in a leftward direction through thecoil 514. When the input-control signal d is low, or “0,” as shown inFIG. 5B,. the direction of the current through the coil is reversed. TheH-bridge switch, shown in FIGS. 5A-B, is but one example of variousdifferent types of electrical and electromechanical switches that can beused to rapidly alternate the direction of current within the coil of anLRVM.

FIG. 6 provides a block diagram of the LRVM, illustrated in FIGS. 4A-G,that represents one implementation of the linear-resonant vibrationmodule to which current application is directed. The LRVM, in additionto the cylindrical housing, coil, and internal components shown in FIG.4A, includes a power supply, a user interface, generally comprisingelectromechanical buttons or switches, the H-bridge switch, discussedabove with reference to FIGS. 5A-B, a central processing unit (“CPU”),generally a small, low-powered microprocessor, and one or moreelectromechanical sensors. All of these components are packaged togetheras an LRVM within a vibration-based appliance, device, or system.

As shown in FIG. 6, the LRVM 600 is controlled by a control programexecuted by the CPU microprocessor 602. The microprocessor may containsufficient on-board. memory to store the control program and othervalues needed during execution of the control program, or,alternatively, may be coupled to a low-powered memory chip 604 or flashmemory for storing the control program. The CPU receives inputs from theuser controls 606 that together comprise a user interface. Thesecontrols may include any of various dials, pushbuttons, switches, orother electromechanical-control devices. As one example, the usercontrols may include. a dial to select a strength of vibration, whichcorresponds to the current applied to the coil, a switch to select oneof various different operational modes, and a power button. The usercontrols generate signals input to the CPU 608-610. A power supply 612provides power, as needed, to user controls 614, to the CPU 616 andoptional, associated memory, to the H-bridge switch 618, and, whenneeded, to one or more sensors 632. The voltage and current supplied bythe power supply to the various components may vary, depending on theoperational characteristics and requirements of the components. TheH-bridge switch 620 receives a control-signal input d 622 from the CPU.The power supply 612 receives a control input 624 from the CPU tocontrol the current supplied to the H-bridge switch 618 for transfer tothe coil 626. The CPU receives input 630 from one or moreelectromechanical sensors 632 that generate a signal corresponding tothe strength of vibration currently being produced by the linearlyoscillating mass 634. Sensors may include one or more of accelerometers,piezoelectric devices, pressure-sensing devices, or other types ofsensors that can generate signals corresponding to the strength ofdesired vibrational forces.

FIGS. 7A-C provide control-flow diagrams that illustrate the controlprogram, executed by the CPU, that controls operation of an LRVM thatrepresents one implementation of the linear-resonant vibration module towhich current application is directed. FIG. 7A provides a control flowdiagram for the high-level control program. The program beginsexecution, in step 702, upon a power-on event invoked by a user througha power button or other user control. In step 702, various localvariables are set to default values, including the variables: (1) mode,which indicates the current operational mode of the device; (2)strength, a numerical value corresponding to the current user-selectedstrength of operation, corresponding to the electrical current appliedto the coil; (3) lvl0, a previously sensed vibrational strength; (4)lvl1, a currently sensed vibrational strength; (5) freq, the currentfrequency at which the direction of current is alternated in the coil;(6) d, the control output to the H-bridge switch; and (7) inc, a Booleanvalue that indicates that the frequency is currently being increased.Next, in step 704, the control program waits for a next event. Theremaining steps represent a continuously executing loop, or eventhandler, in which each event that occurs is appropriately handled by thecontrol program. In certain implementations of the control program,events may be initiated by interrupt-like mechanisms and stacked forexecution while, in more primitive implementations, certain events thatoverlap in time may be ignored or dropped. In the implementationillustrated in FIGS. 7A-C, two timers are used, one for controlling thechange in direction of the current applied to the coil, at a currentlyestablished frequency, and the other for controlling a monitoringinterval at which the control program monitors the vibrational forcecurrently produced. Rather than using a formal timer mechanism, certainimplementations may simply employ counted loops or other simpleprogramming techniques for periodically carrying out tasks. When anevent occurs, the control program begins a series of tasks, the first ofwhich is represented by the conditional step 706, to determine whatevent has occurred and appropriately handle that event. When thefrequency timer has expired, as determined in step 706, the value of theoutput signal d is flipped, in step 708, and output to the H-bridgeswitch, with the frequency timer being reset to trigger a nextfrequency-related event. The frequency-timer interval is determined bythe current value of the variable freq. Otherwise, when the event is amonitor timer expiration event, as determined in step 710, then aroutine “monitor” is called in step 712. Otherwise, when the eventcorresponds to a change in the user input through the user interface, asdetermined in step 714, the routine “control” is called in step 716.Otherwise, when the event is a power-down event, as determined in step718, resulting from deactivation of a power button by the user, then thecontrol program appropriately powers down the device, in step 720, andthe control program terminates in step 722. Any other of various typesof events that may occur are handled by a default event handler 724.These events may include various error conditions that arise duringoperation of the device.

FIG. 7B provides a control-flow diagram for the routine “monitor,”called in step 712 of FIG. 7A. In step 730, the routine “monitor”converts the sensor input to an integer representing the currentvibrational force produced by the LRVM and stores the integer value inthe variable lvl1. Next, in step 732, the routine “monitor” determineswhether or not the LRVM is currently operating in the default mode. Inthe default mode, the LRVM uses continuous feedback control to optimizethe vibrational force produced by the LRVM by continuously seeking tooperate the LRVM at a frequency as close as possible to the resonantfrequency for the LRVM. Other, more complex operational modes may behandled by various more complex routines, represented by step 734 inFIG. 7B. More complex vibrational modes may systematically and/orperiodically alter the frequency or produce various complex,multi-component vibrational modes useful in certain applications,appliances, devices, and systems. These more complex modes areapplication dependent, and are not further described in the control-flowdiagrams. In the case that the operational mode is the default mode, inwhich the, control program seeks to optimize the vibrational forcegenerated by the device, in step 736, the routine “monitor” determineswhether the local variable inc is set to TRUE. if so, then the controlprogram is currently increasing the frequency at which the deviceoperates in order to obtain the resonance frequency. When lvl1 isgreater than lvl0, as determined in step 738, then the vibrational forcehas been recently increased by increasing the frequency, and so theroutine “monitor” increases the frequency again, in step 740, andcorrespondingly resets the frequency timer. Otherwise, when lvl1 is lessthan lvl0, as determined in step 742, then the control program hasincreased the frequency past the resonance frequency, and therefore, instep 744, the control program decreases the frequency, sets the variableinc to FALSE, and correspondingly resets the frequency timer. In similarfashion, when the variable inc is initially FALSE, as determined in step736, and when lvl1 is greater than lvl0, as determined in step 746, theroutine “monitor” decreases the value stored in the variable freq, instep 748 and resets the frequency timer. Otherwise, when lvl1 is lessthan lvl0, as determined in step 750, then the routine “monitor”increases the value stored in the variable freq, sets the variable incto TRUE, and resets the frequency timer in step 752. Finally, the valuein lvl1 is transferred to lvl0 and the monitor timer is reset, in step754.

FIG. 7C provides a control-flow diagram for the routine “control,”called in step 716 in FIG. 7A. This routine is invoked when a change inthe user controls has occurred. In step 760, the variables mode andstrength are set to the currently selected mode and vibrationalstrength, represented by the current states of control features in theuser interface. Next, in step 762, the routine “control” computes anoutput value p corresponding to the currently selected strength, storedin the variable strength, and outputs the value p to the power supply sothat the power supply outputs an appropriate current to the coil.Finally, in step 764, the routine “control” computes a new monitor timerinterval and resets the monitor timer accordingly.

The control program described with reference to FIGS. 7A-C is oneexample of many different implementations of the-control program thatcan be carried out, depending on requirements of the LRVM, theparameters and characteristics inherent in a particular LRVM, the typesof control inputs received from a particular user interface, the natureof the power supply, and the types of operational modes that areimplemented for the LRVM.

FIG. 8 represents the range of frequencies and vibrational forces thatcan be achieved by different implementations of LRVM and LRVM controlprograms that represent embodiments of the current application. FIG. 8has the same axes as the graph shown in FIG. 3. However, unlike FIG. 3,FIG. 8 includes many different curves, such as curve 802, eachrepresenting the vibrational forces and frequencies that can be obtainedfrom a particular LRVM implementation. Again, the LRVMs that representembodiments of the current application generally have a resonantfrequency that is characteristic of the geometry and weights of variouscomponents of the LRVM, and each LRVM is naturally operated at afrequency close to this resonant frequency in order to achieve maximumvibrational force. Thus, rather than being restricted, over all possibleimplementations, to a relatively narrow range of frequencies andvibrational forces, as in the case of unbalanced electrical motors,LRVMs that represent embodiments of the current application can bedesigned and implemented to produce desired vibrational forces over awide range of vibrational frequencies, and desired vibrationalfrequencies over a wide range of desired vibrational forces. Thecontrast is perhaps best seen in FIG. 9. FIG. 9 shows a plot of theamplitude/frequency space and regions in that space that can beoperationally achieved by unbalanced electrical motors and by LRVMs thatrepresent embodiments of the current application. Unbalanced electricmotors can be implemented to produce amplitude/frequency combinations,roughly within the cross-hatched square region 902 withinamplitude/frequency space. By contrast, LRVMs can be designed andimplemented to produce amplitude/frequency combinations underlying curve904. Thus, LRVMs can achieve much higher operational frequencies andmuch lower operational frequencies than can be practically obtained byunbalanced electric motors, and can produce much higher amplitudes andvibrational forces than can be achieved by relatively low-poweredunbalanced electrical motors used in hand-held appliances and othercommonly encountered devices and systems. Furthermore, when largervibrational forces are needed, balanced electrical motors are generallyimpractical or infeasible, due to the destructive forces produced withinthe electrical motors. In general, a single implemented LVM or LVRM canaccess a much larger region of amplitude/frequency space than currentlyavailable vibration modules, which generally operate at fixed amplitudesand/or fixed frequencies, as further discussed below.

FIGS. 10-17 show a variety of different alternative implementations ofLRVMs that represent different embodiments of the current application.FIG. 10 provides a schematic illustration of an LRVM similar to thatdiscussed above with reference to FIG. 4A. Note that, in place of theend magnets 1002 and 1004, mechanical springs may alternatively be used.These may be traditional helical springs made. from metal or springsmade from a compressible and durable material or mechanical device thatseeks to restore its initial shape when depressed or compressed. Notethat the weight and chamber may be cylindrical, in cross section, asdiscussed above with reference to FIG. 4A, or may have other shapes,including rectangular or hexagonal cross-sections.

FIG. 11 shows a similar implementation in which the control unit andpower supply are incorporated into the moving mass 1102. In thisimplementation, the relative masses of the moving mass 1102 andremaining components of the LRVM is maximized, thus maximizing thevibrational forces produced at a given level of power consumption.

FIG. 12 shows yet an alternative LRVM an implementation of thelinear-resonant vibration module to which current application isdirected. In this alternative implementation, additional coils 1202 and1204 are incorporated in the moving mass, and a centering magnet or coil1206 is positioned in a fixed location on the housing so that, when thedirection of the current applied to the coils 1202 and 1204 isalternated, an oscillating rotational force is generated to cause themovable weight to oscillate both in a plane perpendicular to the axis ofthe chamber as well as linearly oscillating the direction of thechamber.

FIG. 13 illustrates an embodiment in which multiple electromagneticcoils are employed. In FIG. 13, two coils 1302 and 1304 are placed intwo different positions on the housing. The first coil 1302 may be usedto drive linear oscillation of the moving mass 1306, while the secondcoil may be activated in order to shorten the length of the chamberwithin which the moving mass linearly oscillates, essentially serving asa second repelling magnet. In this implementation of the LRVM, themoving mass may linearly oscillate with at least two differentamplitudes, depending on whether or not the second coil 1304 isactivated to repel the moving mass. Additionally more complex patternsof current reversal in the two coils can be employed to produce complexmulti-component vibrational modes of the moving mass.

When the housing is fully enclosed, air within the chamber serves todampen oscillation of the moving mass. This dampening may be minimizedby providing channels, on the sides of the moving mass, to allow air topass from one side of the moving mass to the other, by channels throughthe moving mass, or by providing openings in the housing to allow air tobe forced from the housing and drawn into the housing. Additionally,different fluids or liquids may be employed within the chamber to changethe dampening effect produced by displacement of the fluids and gassesas the moving mass linearly oscillates.

FIG. 14 illustrates an alternative LRVM an implementation of thelinear-resonant vibration module to which current application isdirected in which a plunger linearly oscillates to produce a vibration.The plunger 1402 is slideably contained within a moveable-componenttrack orthogonal to a long axis of the main housing 1404 of the LRVMthat includes the power supply, microcontroller, and other controlcomponents. The plunger is girdled by, or includes, a driving magnet1406 that is attracted to, and seeks to be positioned in alignment with,a centering magnet 1408 mounted within the housing. Applying current toone of two driving coils 1412 and 1414 forces the driving magnet awayfrom the equilibrium position shown in FIG. 14. By rapidly switching thedirection of current applied to the driving coils, the microcontrollercan control the plunger to linearly oscillate in an up-and-down fashion,as indicated by arrow 1420.

FIG. 15 shows yet another LRVM an implementation of the linear-resonantvibration module to which current application is directed. In this animplementation of the linear-resonant vibration module to which currentapplication is directed, a spring-like member 1502 is clamped at one end1504 to the housing. Driving magnets 1506 and 1508 are fixed to thespring-like member 1502, and when current is rapidly reversed in a coil1510, the spring-like member 1502 is induced to vibrate at a relativelyhigh frequency.

FIG. 16 shows an alternative an implementation of the linear-resonantvibration module to which current application is directed similar to theembodiment shown in FIG. 15. In this embodiment, the spring member 1602is extended to provide an external massage arm 1604 that extends outfrom the housing to provide a linearly oscillating massage-foot member1606 for massaging human skin or some other substrate, depending on theapplication.

FIG. 17 shows a mechanical vibration adjustment feature that can beadded to either of the embodiments shown in FIGS. 15 and 16. Anadjustment screw 1702 can be manipulated to alter the position of amovable spring clamp 1704 that acts as a movable clamping point for thespring-like member 1706. Moving the movable spring clamp 1704 leftward,in FIG. 17, shortens the length of the spring-like member and thus tendsto increase the resonant frequency at a particular power-consumptionlevel. Conversely, moving the movable spring clamp rightward, in FIG.17, lengthens the spring-like member and decreases the vibrationalfrequency.

FIG. 18 illustrates an enhancement of an implementation of thelinear-resonant vibration module to which current application isdirected shown in FIG. 16. In this embodiment, the massage foot isenhanced to include elastomer bristles 1802-1805 to transfer the linearoscillation of the massage foot to human skin or another substrate. Theelastomeric bristles, or pad or brush comprising numerous elastomericbristles, allow transmission of vibration to a surface even at lowoperational powers, when a rigid or even semi-compliant massage footwould instead simply stop moving for inability to overcome frictionalforces.

As discussed above with reference to FIG. 6, including a processor ormicrocontroller within a linear-resonant vibration module allows for avery large number of different processor-controlled vibration patternsand modes to be exhibited by the linear-resonant vibration module. Asdiscussed above, processor control along with alinear-resonant-vibration-module architecture allows theprocessor-controlled device to access a much larger portion of a totalamplitude/frequency space than can be accessed by currently availableunbalanced-electric-motor vibration devices. Thus, processor-controlledlinear-resonant vibration modules provide a large increase infunctionality with respect to currently available vibration modules.There is, however, a relatively large gap in functionality betweenprocessor-controlled linear-resonance vibration modules and currentlyavailable unbalanced-electric-motor vibration modules that can bebridged by linear vibration modules that lack processor ormicroprocessor control.

When discussing vibration modules, electric motors, and otheroscillating devices, it is common to use the phrase “Q factor,” or“quality factor,” to refer to a quality or characteristic of anoscillating device. The Q factor refers to the level of dampening of anoscillator or, in other words, a ratio of the energy stored in theoscillator or resonator to the energy needed to be supplied to theoscillator or resonator during each oscillation cycle in order tomaintain a constant oscillation amplitude. FIG. 19 illustrates. plots ofamplitude versus frequency for a high-Q and a low-Q vibration device.The curve 1902 for a high-Q device generally has a narrower and talleramplitude peak about a resonant frequency 1904 or, in certain cases,several relatively tall, narrow peaks about several resonantfrequencies, while a low-Q device exhibits a much broader, butlower-amplitude amplitude-versus-frequency curve 1906. A linear-resonantvibration module, when controlled to vibrate at a resonant frequency, asdescribed above, generally operates as a high-Q device. However, whencontrolled by user input or programmatically to vibrate at non-resonantfrequencies, the linear-resonant vibration module may instead operate asa low-Q device. Linear vibration modules and other types of vibrationmodules that lack feedback control generally do not operate at resonantfrequencies for extended periods of time, and thus tend to be low-Qdevices.

Unbalanced-electric-motor vibration modules and even currently availableresonating motors generally operate at either a fixed amplitude or afixed frequency. For example, unbalanced-electric-motor vibrationmodules are generally operated at high revolutions per minute (“RPM”) tocreate any vibration, and once operating at a given speed have arelatively fixed amplitude determined. by the geometry of the unbalancedweight and rotor shaft. Other types of vibration modules that arecurrently available include resonating motors, such as the vibrationmodules found in certain electric toothbrushes, but these resonatingmotors operate only at a fixed frequency. In both cases, only a verylimited portion of the amplitude/frequency space can be accessed byessentially fixed-amplitude or fixed-frequency vibration modules.

Alternative, lower-cost linear-vibration modules can be designed andmanufactured by replacing the processor or microcontroller (602 in FIG.6) of the above-described linear-resonant vibration module with asimpler oscillator circuit with additional control circuitry. The Hswitch (620 in FIG. 6) can be controlled by an oscillating current inputrather than digital outputs from a microprocessor. Replacing the CPU ormicroprocessor with an oscillator and additional simple controlcircuitry produces a less functional, generally lower-Q, but also moreeconomical linear vibration module that, although lacking the extremelybroad range of vibration patterns and modes available to processor ormicroprocessor-controlled vibration modules, can nonetheless access amuch larger portion of the amplitude/frequency space than can beaccessed by currently available fixed-amplitude or fixed-frequencyvibration modules.

In one example implementation of an oscillator-controlled linearvibration module, a variable-frequency oscillator circuit can becontrolled by user input to drive the H switch or other H-switch-likecircuit to operate the linear vibration module at different frequencies.A user is provided an input feature that allows the user to directlyadjust the frequency of the variable oscillator and thus the vibrationalfrequency produced by the linear vibration module. The user isadditionally provided with an input feature to allow the user to controlthe current or duty cycle used to drive the linear vibration module andto thus increase and decrease the amplitude of vibration produced by thelinear vibration module. Thus, a user can control both the frequency ofvibration and the amplitude of vibration.

FIG. 20 illustrates portions of amplitude/frequency space accessible tovarious types of vibration modules. In FIG. 20, frequency is plottedwith respect to a horizontal axis 2002 and amplitude is plotted withrespect to a vertical axis 2004. The plane indexed by these axesrepresents the amplitude/frequency space, portions of which can beaccessed by a given type of vibration module. The above-describedunbalanced-electric-motor vibrators are essentially constant-amplitudedevices, and can thus access some range of frequencies at a fixedamplitude, represented by line segment 2006 in FIG. 20. Differentunbalanced-electric-motor vibrators may have different fixed amplitudes,but, for a given device, the portion of amplitude/frequency space thatthey can access can generally represented by a line segment orhigh-aspect-ratio rectangle oriented orthogonally to the amplitude axis.The resonant-motor vibration devices, which each operates at a fixedfrequency, can generally access a range of amplitudes at the. fixedfrequency, as represented by line segment 2008 in FIG. 20. By contrast,a linear vibration. module user-input-controlled variable frequency andvariable amplitude can access a two-dimensional subspace within theamplitude/frequency space, such as the region 2010 within ellipticalboundary 2012 in FIG. 20. Clearly, a linear vibration module withuser-controlled variable amplitude and variable frequency can provide amuch broader range of amplitude/frequency combinations than currentlyavailable vibration modules. A processor or microcontroller-controlledlinear-resonant vibration module, as discussed above with reference toFIGS. 4A-18, can access an even larger region of amplitude/frequencyspace that includes region 2010 with a subspace.

In certain low-Q linear vibration modules that lack microprocessor ormicrocontroller control, for any given frequency of operation, theamplitude tends to increase with decreasing frequency of operation. FIG.21 illustrates the dependence between frequency and amplitude in a low-Qlinear vibration module as well as a modified dependence that can beobtained by control circuitry. In FIG. 21, solid curve 2102 representsthe dependence of amplitude on frequency for a low-Q linear vibrationmodule without additional control circuitry. As the frequency decreases,the amplitude begins to steeply and non-linearly increase. In certainapplications, a constant or relatively constant amplitude is desiredover a broad range of frequencies. A low-Q linear vibration modulewithout microprocessor or microcontroller control can obtain a moreconstant amplitude over a broader range of frequencies by adjusting thecurrent or duty cycle downward at lower frequencies. For example, asshown by dashed curve 2104 in FIG. 21, the control circuitry can beimplemented to detect when user-input-controlled operational frequencyof a linear vibration module is below a threshold frequency 2106, atwhich point control circuitry can lower the driving current or dutycycle to decrease the vibrational amplitude when the linear vibrationmodule is operating at frequencies below the threshold frequency. Thus,dashed curve 2104 is the sum of a lowered-current low-frequency curveand a higher-current high-frequency curve, with the curves joined at thethreshold frequency. Alternatively, control circuitry can be implementedto continuously adjust the current or duty cycle lower as the frequencyof operation is lowered by user input in order to even further flattenthe amplitude-versus-frequency curve for the linear vibration module. Ineither case, a user may override these automatic adjustments byincreasing the amplitude at lower operational frequencies via user inputto an amplitude-control user-input feature.

Returning to microprocessor-controlled or microcontroller-controlledlinear vibration modules, it should be noted that processor ormicroprocessor control allows for an essentially limitless number ofdifferent vibrational behaviors and modes to be configured by softwareor firmware design, by user input, or by a combination of software orfirmware design and user input. Rather simple enhancements can produceinteresting enhanced vibrational behavior. As one example, amicroprocessor-controlled or microcontroller-controlled linear vibrationmodule can be programmed to drive the device simultaneously at twodifferent frequencies. FIGS. 22A-23 illustrate interesting vibrationalmodes produced by driving a linear-resonant vibration modulesimultaneously at two different frequencies. FIG. 22A shows a vibrationmode of a linear vibration module driven at a frequency of 25 Hz. In aone-second duration of time, plotted with respect to horizontal axis2202, 25 cycles, each including a positive and negative amplitude peak,such as positive amplitude peak 2204 and negative amplitude peak 2206,occur. At a constant 25 Hz frequency of operation, the positive peaksand negative peaks are evenly spaced. FIG. 22B illustrates a vibrationmode of the linear vibration module driven at a primary operationalfrequency of 25 Hz with an added modulating 1 Hz operational frequency.Driving the linear vibration module by both a primary and a modulatingfrequency produces low-frequency pulses of high-frequency vibration.FIG. 23 illustrates a different complex vibrational mode in which twodriving frequencies combine to produce a lower-frequency beat-wave form.The vibrational mode illustrated in FIG. 23 is produced by a primarydriving frequency of 25 Hz, as in FIG. 22A, with a second drivingfrequency of 20 Hz. By varying the number, relative amplitudes, andfrequencies of two or more driving signals, a microprocessor-controlledor microcontroller-controlled linear-resonance vibration module can becontrolled to produce any number of complex vibrational patterns andmodes, including periodic modes, modes with multiple different periods,various modulated vibration modes, and even fully a periodic vibrationmodes that do not repeat time.

In a linear-resonant vibration module, discussed above, by maintainingdevice operation at a resonant frequency, the linear-resonant vibrationmodule is a relatively high-Q device, and generally operates moreefficiently to produce a given vibration amplitude than a low-Q device,such as a linear vibration module lacking microprocessor ormicro-controller control and operating at a frequency/amplitude settingthat does not correspond to a natural vibration mode of the device.There are, in addition, many other ways to increase the energyefficiency of a linear vibration module.

FIGS. 24A-25 illustrate incorporation of paramagnetic flux paths into alinear vibration module. In free air, magnetic field lines radiateoutwards in arcs from the north pole to the south pole of a magnet,completing a magnetic circuit. Free air can be considered to beanalogous to a resistor in an electric circuit and increases theresistance, or magnetic reluctance, of a magnetic circuit and reducesand the flux of the magnetic field. A magnetic field seeks out the pathof least resistance, and changes direction, when necessary, to maximizeflux between the two magnetic poles. When introduced into a magneticfield, paramagnetic materials provide a lower-resistance path formagnetic flux, providing that they have adequate permeability and sizeto avoid saturation. Paramagnetic materials of appropriate permeabilityand size reduce the reluctance of a magnetic circuit and can thereforeallow a magnetic field to more efficiently perform more work.

FIG. 24A shows a linear vibration module without paramagnetic fluxpaths. On the left-hand side of FIG. 24A, the magnetic field lines 2402of the moving magnet are shown. A significant portion of the magneticfield lines can be seen to pass through air. FIG. 248 shows a linearvibration module with added paramagnetic flux paths. These include fluxpaths around the stator coils 2410-2411 as well as flux-path disks2414-2415 at the ends of the cylindrical magnet 2416 within the linearvibration module. As can be seen by comparing FIG. 24B to FIG. 24A, onlytiny portions of the flux lines in FIG. 24B pass through free air, incontrast to the relatively large portions of flux lines that passthrough free air in FIG. 24A. Thus, addition of paramagnetic flux pathsto a linear vibration module in order to decrease the portion ofmagnetic field lines passing through free air provides a more efficientlinear vibration module.

FIG. 25 illustrates flux-path magnetic stops incorporated within alinear vibration module to which the current application is directed.During operation of the linear vibration module, and without theinfluence of any external force on the piston, the mid-plane of theshuttle magnet 2502 oscillates about the fixed mid-plane of thecentering magnet 2504. When the device encounters a resisting normalforce on the end of the piston, the shuttle magnet biases into the motorand oscillates about a datum offset from the fixed mid-plane of thecentering magnet. When the resisting force is greater than theelectromagnetic force generated by the motor, the piston assemblycontinues to be driven into the bore until the flux disc 2506 is in linewith the return lip 2508 of the flux path. En this position, the air gapof the magnetic circuit is reduced due to the proximity of the flux discto the return lip. Maximum magnetic flux flow is achieved between thesetwo components in a radial direction. Additional external axial force isrequired to force the piston assembly to move beyond this limit,effectively producing a magnetic stop. This effect also prevents thepiston from being ejected from the motor at high power and low frequencysettings at which the piston carries significant momentum.

Although the present invention has been described in terms of particularembodiments, it is not intended that the invention be limited to theseembodiments. Modifications will be apparent to those skilled in the art.For example, as discussed above, LRVMs can be designed to producedesired vibrational amplitudes and frequencies over a wide region ofamplitude/frequency space by varying various different design parametersand characteristics, including the amplitude of a moving mass thatlinearly oscillates within the LRVM, altering the dimensions of the LRVMand internal components of the LRVM, altering the weight of the movingmass and other components of the LRVM, changing the ratio of the movingmass to the ratio of the remaining components of the LRVM, increasing ordecreasing the number of turns in the coil or coils used to drive linearoscillation, increasing or decreasing the current supply to the coils,altering the dampening produced by displacement of fluid or gas by themoving mass within the LRVM as well as by various additional frictionalforces, altering the strength of the end-cap magnets or mechanicalsprings used to facilitate reversal of direction of the moving mass, andby changing any of various additional parameters and characteristics.Any of various different microprocessors and other microcontrollers canbe used in alternative embodiments of the LRVM, as well as differentpower supplies, current-switching devices, and other components. Thecontrol program executed by the LRVM can be implemented in manydifferent ways by varying any of many different design parameters,including programming language, control structures, data structures,modular organization, and other such design parameters. The componentsof the LRVM, including the housing, moving mass, fixed magnets, andelectromagnets, can be fashioned from many different types of materials,from polymers and plastics to metals and alloys in various compositematerials. LRVMs may contain one, two, or more electromagnets and/orpermanent magnets in order to produce linear oscillation of a movingmass or spring-like mass, and various different control programs can beimplemented to produce many different types of single-component andmulti-component vibrational modes, some of which may regularly orerratically change, over time, to produce a wide variety of differenttypes of vibrational characteristics. An additional housing made from amaterial with a relatively large Magnetic permeability can be added tovarious embodiments of the current application to concentrate andincrease the linear magnetic forces produced by the various coils.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that the specificdetails are not required in order to practice the. invention. Theforegoing descriptions of specific embodiments of the present. inventionare presented for purpose of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Many modifications and variations are possible in view of theabove teachings. The embodiments are shown and described in order tobest explain the principles of the invention and its practicalapplications, to thereby enable others skilled in the art to bestutilize the invention and various embodiments with various modificationsas are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalents:

The invention claimed is:
 1. A linear vibration module comprising: ahousing; a moveable component; a power supply; user-input features; adriving component that drives the moveable component in each of twoopposite directions within the housing; a control component thatcontrols supply of power from the power supply to the driving componentto cause the moveable component to oscillate at a frequency and anamplitude specified by user input received from the user-input features;and flux paths comprising a paramagnetic material that is shaped andpositioned to reduce the reluctance of one or more magnetic circuitswithin the linear vibration module.
 2. A linear vibration modulecomprising: a housing; a moveable component; a power supply; user-inputfeatures; a driving component that drives the moveable component in eachof two opposite directions within the housing; and a control componentthat controls supply of power from the power supply to the drivingcomponent to cause the moveable component to oscillate at a frequencyand an amplitude specified by user input received from the user-inputfeatures, wherein the control component drives simultaneous oscillationof the moveable component at two or more frequencies to generate complexvibration modes.
 3. The linear vibration module of claim 2 wherein thecomplex vibration modes include: a primary oscillation frequencymodulated by a modulating oscillation frequency; a beat frequency; andan aperiodic oscillation waveform.
 4. A linear vibration modulecomprising: a housing; a moveable component; a power supply; user-inputfeatures; a driving component that drives the moveable component in eachof two opposite directions within the housing; and a control componentthat controls supply of power from the power supply to the drivingcomponent to cause the moveable component to oscillate at a frequencyand an amplitude that are independently specified by user input receivedfrom the user-input features.
 5. A linear vibration module comprising: ahousing; a moveable component; a power supply; user-input features; adriving component that drives the moveable component in each of twoopposite directions within the housing; a control component thatcontrols supply of power from the power supply to the driving componentto cause the moveable component to oscillate at a frequency and anamplitude specified by user input received from the user-input features;and elastomeric bristles used to transfer vibration from the linearvibration module to a surface.